Rolling mill of the pilger type



Patented Aug. 13, 1929.

UNITED STATES PATENT OFFICE.

EWALD RIBER, F DUSSELDORF, GERMANY.

ROLLING MILL OF THE PILGER TYPE.

Application filed June'29, 1926, Serial No. 119,287, and in Germany November 25, 1925. 1

1 the mandrel and work attached thereto is pushed back after each individual operation of the pilger rolls exactly to the point at which the work is to be seized by the rolls in their next operation.

The means used hitherto for pushing back the work consisted in springs ten'sioned during each back stroke of the rod and mandrel or in air compressed in a cylinder, the clasticity of the springs or air being used to push back the rod and the work attached thereto at the end of each operation of the rolls. This return mot-ion of the rod and work produced by elastic means is, however, very difficult to control and requires the use of complicated braking devices. It is therefore been proposed that non-elastic members such as a push rod driven by a crank on the roll shaft be used to produce the return motion. Such a rigid connection between the mandrel feed rod and its drive is, however, impracticable because the return travel of the work at each operation of the rolls is not always equal in length, due to the peculiar action of the rolling process.

I avoid the shortcomings of known devices by eifecting the return motion of the mandrel feed bar by a means which, although it is non-elastic, does not effect a rigid connection between the feed bar and the drive. This means consists in a column of liquid arranged to be shifted in a cylinder.

An embodiment of my invention is illustrated in the drawing which represents a longitudinal section of the device for feeding the work through the rolls.

The mandrel with the'work 1 that is subjectedto the action of the rolls 2 is attached in a known manner to a mandrel feed rod 3, the rear end of which is shaped in the form of a plunger 4 with a head 5 that is arranged to move in a cylinder 6. The front end of the cylinderG is closed by the annular plate 7 and its rear end is closed by a plate 8. The plunger 4 extends through .a stuffing box 9 in the front plate 7. In the 'frontend of the cylinder 6, whose bore is somewhat larger than that of its rear end, there is a nected by a short duct 12 and a round passage 13 to a second cylinder 14, in which is placed a hollow piston 15 with a closed bottom 16. The inner wall of the piston 15 slides against a hollow body 17 that is rigidly attached to the cylinder 14 by staybol ts 19 and a bridge member 18. The piston 15 is sealed externally by a stuffing box 20 and internally by a stufiing box 21. In the bottom 16 of the piston 15 is a circular rccess 22 in which a circular plate 23 can be shifted axially by means of a spindle 24 that can be turned by ahand wheel 25. The part of the plate 23 that protrudes beyond the bottom 16 extends into the passage 13 when the piston 15 is in its lowermost position, the diameters of 23 and 13 being such as to leave a small amount of play.

The device operates in the following man ner: The interior of the cylinder 6 i filled with water, while the hollow body 17 con-- talns compressed air. Assuming that the combined feed and plunger rod 3, 4 moves into the cylinder to the position shown di1rmg an operation of the roll, a part of the water will beforced out of the cylinder 6 and will pass through the passage 13 into cylinder 14 where it lifts the piston 15- and causes further compression of the compressed air in the hollow body 17. At the end of the operation of the rolls 2, 2the air presses the piston 15 down again which, in turn forces the water back into the cylinder 6. This rushing back of the water is,

however, impeded when the piston 15 approaches the end of. its return stroke by the entrance of the plate 23 into the passage 13. This also slows down the motion of the plunger 4 so that it exerts onlya slight blow when it reaches the forward end of its stroke. This slight blow is taken by the braking or buffer device 10, 11, because the head 5 of the plunger 4 strikes the pis- .ton l0 shortly before the plunger 4 reaches the end of its forward travel and the piston 10 abuts upon the spring 11. An ordinary spring would also exercise a cushioning effect, but it would return the blow to the plunger 4 so that the plunger would only come to rest after a number of oscillations. To avoid these oscillations I prefer to employ a spring which is similar to the butter springs used on railway carriages which comprises internal friction members. The internal friction in the spring consumes most of the force that compresses it so that its force of expansion can not throw back the plunger. If the plate 23 is carefully adjusted the braking device 10, 11 hardly needs to act at all.

I claim 1. In a rolling mill, the combination of a liquid-containing cylinder, a reciprocable mandrel feed bar, a plunger carried by said feed bar and extending within said cylinder,

a second cylinder in communication with said first cylinder, a movable piston in said second cylinder, and a hollow body concentrically disposed within the second cylinder and rigidly secured thereto, said hollow body being adapted to contain a compressible medium, the organization being such that movement of the feed bar in one direction will cause the liquid in said first cylinder to move said piston thereby to compress said medium.

2. In a rolling mill, the combination of a liquid-containing cylinder, a reciprocable mandrel feed bar, a plunger carried by said bar and extending into said cylinder, a second cylinder in communication with the interior of the first cylinder, a hollow body concentrically disposed within said second cylinder and rigidly secured thereto, saidhollow body being adapted to contain a compressible medium, a movable piston in said second cylinder and having a recessed bottom adapted to cooperate with the hollow body for compressing said medium, seals between the piston and second cylinder and between the piston and the hollow body for preventing escape of said medium, and a movable plate disposed in the recess in the bottom of piston and adapted to cont-r01 the communication between the cylinders.

In testimony whereof I have signed my name to this specification.

EWALD RGBER. 

